fopen does not work when put text code

fidfi =fopen('for_1780.lgt');
textDatafi = textscan(fidfi, '%s%s%s%s','delimiter', ' ');
fclose(fidfi);
 
gtitle = [textDatafi{1,2}{7,1}]; %extraction of file name
splitgtitle = extractAfter(gtitle,12); 
lgttext = (".lgt'");
Roriginaltitle = insertBefore(splitgtitle,1,"'rev_"); %for reverse file name
Fullrname = strcat(Roriginaltitle,lgttext);

fidri = fopen(Fullrname); 
textDatari = textscan(fidri, '%s%s%s%s','delimiter', ' ');
fclose(fidri);

I thought after making the charactor "'rev_1780.lgt'", if the charactor is put in the "fidri = fopen(Fullrname);", it will run well. However, the code gave me integer -1.

What's the problem? if I see the matrix, they show "'rev_1780.lgt'" but it did not work.... the 'rev_1789' file is located in the same folder with 'for_1780.lgt'

sorry I copyed wrong way. I changed code again in the original file there is no typo.

So if I copy and paste of the Fullrname's data at the fopen, really it woked well. However, when I put Fullrname directly, it did not work.

Additionally,

[fidri, msg] = fopen(Fullrname);

if fidri < 0

error('Could not open file "%s" because "%s"', Fullrname, msg)

end

Although changed to this code instead of fidri = fopen(Fullrname);, just they showed error msg.

Could not open file "'rev_1780.lgt'" because "No such file or directory"

I work at the folder where the file is. should I do code more something?

To. Walter Roberson

could you please explain precisely? how can I show the output ?

Additionally, this is my coding now. Unfortunately, could not upload lgt file here

clear
clc



%% for obtaing information of data (forward)
fidfi =fopen('for_1780.lgt');
textDatafi = textscan(fidfi, '%s%s%s%s','delimiter', ' ');
fclose(fidfi);

gtitle = [textDatafi{1,2}{7,1}]; %extraction of file name
splitgtitle = extractAfter(gtitle,12); 


lgttext = (".lgt'");
Roriginaltitle = insertBefore(splitgtitle,1,"'rev_"); %for reverse file name
Fullrname = strcat(Roriginaltitle,lgttext);

ls rev_1780.*

[fidri, msg] = fopen(Fullrname);
if fidri < 0
    error('Could not open file "%s" because "%s"', Fullrname, msg)
    

end
textDatari = textscan(fidri, '%s%s%s%s','delimiter', ' ');
fclose(fidri);

In the command window, it showed

rev_1780.lgt

Could not open file "'rev_1780.lgt'" because "No such file or directory"

[Geoff Hayes]

jaekeun - is this just a typo

Fullrname = strcat(Roriginaltitle,lgttext);
fidri = fopen(Fullrnam); 

? You create the variable Fullrname but then use Fullrnam when trying to open the file.

If the above is just a typo (and not in your original code), have you confirmed that Fullrname is the correct name of a file in the current folder?

[Walter Roberson]

Fullrname = strcat(Roriginaltitle,lgttext);
fidri = fopen(Fullrnam); 

First line involves a variable that has an 'e' at the end. Second line involves a variable with no 'e'.

[Walter Roberson]

Change

fidri = fopen(Fullrname); 

to

[fidri, msg] = fopen(Fullrname);
if fidri < 0
    error('Could not open file "%s" because "%s"', FUllrname, msg)
end

[jaekeun lim]

Additionally,

[fidri, msg] = fopen(Fullrname);

if fidri < 0

error('Could not open file "%s" because "%s"', Fullrname, msg)

end

Although changed to this code instead of fidri = fopen(Fullrname);, just they showed error msg.

Could not open file "'rev_1780.lgt'" because "No such file or directory"

I work at the folder where the file is. should I do code more something?

[Walter Roberson]

Please show the output of

ls rev_1780.*

[jaekeun lim]

To. Walter Roberson

could you please explain precisely? how can I show the output ?

[Stephen23]

"could you please explain precisely?"

We want to know what files are actually in that directory. Only you can help us by following Walter Roberson's request, which is to run a command with a specific input. The command is ls, the input is 'rev_1780.*'

"how can I show the output ?"

You can copy-paste that command into the command window, like this:

>> ls rev_1780.*

and then press enter. The command will run, and print some output in the command window. Walter Roberson asked you to show us that output.

[jaekeun lim]

In the command window, it showed

rev_1780.lgt

Could not open file "'rev_1780.lgt'" because "No such file or directory"

[Stephen23]

@jaekeun lim : I do not understand how you get a message like "Could not open file..." from running the ls command.

Type this in the command window:

>> ls *1780.*

and show us the complete printed output.

[jaekeun lim]

@Stephen Cobeldick

from the ls *1780.*

I got rev_1780.lgt

Could not open file "'rev_1780.lgt'" because "No such file or directory" is from the "if" function

[Stephen23]

@jaekeun lim : Please show the output of these two commands:

>> ls *.*
>> disp(Fullrname)

Please just copy and paste the entire section from the command window, including the commands themselves. Do not edit or change it.

[jaekeun lim]

@Stephen Cobeldick

>> ls *.*

disp(Fullrname)

for_1780.lgt rev_1780.lgt untitled.m

'rev_1780.lgt'

>>

Answer 1

[Stephen23]

You are adding extra single quotes, here:

lgttext = (".lgt'");
%               ^ superfluous
Roriginaltitle = insertBefore(splitgtitle,1,"'rev_");
%                                            ^ superfluous

These single quotes are causing the problem. Get rid of them.

Either use character arrays:

lgttext = ('.lgt');
Roriginaltitle = insertBefore(splitgtitle,1,'rev_');

or string arrays, whichever you prefer. But there is no point in adding extra single quotes to those strings, which serve no obvious purpose.

Personally I find that filename conversion overly complex, and would just do something like this:

>> inp = 'for_1780.lgt'
inp =
for_1780.lgt
>> out = strrep(inp,'for_','rev_')
out =
rev_1780.lgt

[jaekeun lim]

@Stephen Cobeldick

Really Thank you so much !

After removing single quotes, it works well. By the way, I wonder one thing that normally when fopen function is used, single quotes are used between file name. However, in this case, without single quotes, file name is put.

Why is it different?

[Stephen23]

"..normally when fopen function is used, single quotes are used between file name..."

Not at all:

• Single-quotes are an operator that creates a character vector.
• Double-quotes are an operator that creates a scalar string.

Do not confuse those operators with actually having those characters inside the character vector or string itself: they are NOT part of the character vector/string!

The function fopen requires its first argument to be a character vector or a scalar string, but it really knows nothing at all about how strings/character vectors are defined.

"However, in this case, without single quotes, file name is put. "

I have no idea what that means. But you seem to be confusing the operators that create character vectors and strings (which, just like in many other languages, are denoted in the code by ' and "), with those characters actually occuring inside the character vector or string.

"Why is it different?"

What is different?

MATLAB is quite consistent:

• "abc" defines a scalar string containing the three characters abc.
• 'abc' defines a 1x3 character vector containing the characters abc.

Neither the string nor the character vector contains the characters " or '.

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